The present invention relates to novel compositions comprising fluorocarbons and hydrocarbons, and to novel compositions comprising fluorocarbons, hydrocarbons and water.
Fluorocarbon based fluids have found widespread use in industry in a number of applications, including as refrigerants, aerosol propellants, blowing agents, heat transfer media, and gaseous dielectrics. Because of the suspected environmental problems associated with the use of some of these fluids, it is desirable to use fluids having low or even zero ozone depletion potential, such as hydrofluorocarbons (xe2x80x9cHFC""sxe2x80x9d).
Thus, the use of fluids that do not contain chlorofluorocarbons (xe2x80x9cCFCsxe2x80x9d) or hydrochlorofluorocarbons (xe2x80x9cHCFCsxe2x80x9d) is desirable. Additionally, it is known that the use of single component fluids or azeotropic mixtures, which mixtures do not fractionate on boiling and evaporation, is desirable. However, the identification of new, environmentally safe, non-fractionating mixtures is complicated due to the fact that azeotrope formation is not readily predictable.
The art continually is seeking new fluorocarbon based mixtures that offer alternatives to, and are considered environmentally safer substitutes for, CFC""s and HCFCs. Of particular interest are combinations or mixtures containing a fluorocarbon and a non-fluorocarbon, both of low or no ozone depletion potentials. Such mixtures are the subject of this invention. As used herein, the term fluorocarbon includes CFCs and HCFCs.
The present inventors have developed several compositions that can help to satisfy the continuing need for substitutes for CFCs and HCFCs. In one embodiment, the present invention provides azeotrope-like compositions comprising pentafluoropropane, at least one C4 hydrocarbon and water. In other embodiments, the present invention provides azeotrope-like compositions comprising pentafluoropropane, preferably 1,1,1,3,3-pentafluoropropane (hereinafter xe2x80x9cHFC-245faxe2x80x9d), and from about 1 to less than about 30 percent by weight of isobutane. In yet further embodiments, the present invention provides azeotrope-like compositions comprising pentafluoropropane and propane.
The preferred compositions of the invention provide environmentally desirable, zero ozone depletion potential replacements for currently used CFC""s and HCFC""s. Additionally, the compositions of the invention exhibit characteristics that make the compositions better CFC and HCFC substitutes than any of HFC-245fa, isobutane, propane or water alone.